Chem Basis: Steroids 3

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    A C21 ester is active at GC recptors?
    • False, it is a prodrug
    • Free C21-OH is required for corticoid binding
    • Must hydrolyze before activity can be achieved
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    How can you alter the lipophilicity of this molecule?
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    • Enhance lipophilicity: Esterify the C21 with a lipophilic acid
    • Reduce Lipophilicty: Esterify the C21 with an acid that will create a charge of 7.4
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     A lipophilic ester at the C21 effects what characteristics of this molecule?
    • More H20 insoluble
    • Reduces systemic side effects
    • Increases localization of action
    • Slows the OOA
    • Prolongs the DOA
    • Enhances topical use
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    Why does a lipophilic ester at the C21 give the molecule more localized action?
    Higher Log P limits systemic distribution
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     Why does a lipophilic ester at the C21 give the molecule reduced systemic side effects?
    Higher Log P limits systemic distribution
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    Why does a lipophilic ester at the C21 give the molecule reduced OOA?
    Slow release of the C21-OH from the ester prodrug form to the active free C21-OH form
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    Why does a lipophilic ester at the C21 give the molecule a prolonged DOA?
    • Hydrolysis to the active C21-OH is slow
    • Resistant to C17 oxidation to the inactive 17 keto steroid
    • Does not concentrate in the kidney
    • Undergoes tubular reabsorption if it does make it to the kidney
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    Why does a lipophilic ester at the C21 give the molecule better topical action?
    • High Log P allows for better skin penetration
    • Cannot readily redistribute or absorb (unless skin is broken)
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     What are lipophilic C21 ester prodrugs used for?
    • Internally: chronic therapy
    • Topically: for dermatitis
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    Why are lipophilic C21 ester prodrugs a good choice for internal chronic therapy?
    Longer DOA = fewr doses = better compliance
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    By what route would a lipophilic C21 ester prodrug be given?
    • Topically
    • PO
    • Inhalation
    • Oil based depo
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    Would you need more or less drug to achieve appropriate action with an C21 ester prodrug and why?
    Less, due to the longer DOA
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    Is this drug lipophilic or hydrophilic?
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    • Lipophilic
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     Is this drug lipophilic or hydrophilic?
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    • Lipophilic
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    What is this function group called?
    Acetate
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    A hydrophilic C21 prodrug ester has what characteristics
    • Useful IV and IM
    • Mostly charged at pH 7.4
    • Wide systemic distribution and side effects
    • Rapid OOA
    • Short DOA
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    Why does a hydrophobic ester at the C21 give the molecule better distribution?
    Water soluble, so easily transported in the blood
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    Why does a hydrophobic ester at the C21 give the molecule better IV and IM administration capabilities?
    Water soluble
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     Why does a hydrophobic ester at the C21 give the molecule a more rapid OOA than a lipophilic ester?
    • Easily absorbed into the plasma and transported
    • Esterases are readily available in the plasma
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    Why does a hydrophobic ester at the C21 give the molecule a shorter DOA than a lipophic ester?
    • Water soluble = rapidly excreted by the kidney and not reabsorbed
    • Oxidation to 17-keto steroid is much faster since it is readily hydrolyzed by plasma esterases
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    A hydrophobic ester at the C21 will be neutral or charged at physiological pH?
    Charged
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    What routes of administration are available for a hydrophobic ester at the C21?
    PO, injection, inhalation and topical
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    Why is a hydrophilic C21 ester prodrug less desirable topically than a lipophilic ester?
    • Greater systemic distribution and skin penetration
    • Leads to greater side effects
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    Is this a lipophilic or hydrophilic prodrug?
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    • Hydrophilic
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     Is this a lipophilic or hydrophilic prodrug?
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    • Hydrophilic
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    What is this group called?
    Sodium phosphate
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    What is this group called?
    Sodium succinate
  28. What is a diether?
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    • C21 ether + either a 17B or 16a ether
    • (picture is an example of a dipropionate ester)
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     The function group attached to the D ring in these images is classified as what type of group?
    Ketel (cyclic gem-diether)
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    What characteristics must this Carbon have?
    No Hydrogens attached
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    What is the specific name for this functional group?
    Acetonide
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    Is this drug active or is it a prodrug?
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    • Active
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    What is the specific name for this functional group?
    Hexacetonide
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    Is this drug active or is it a prodrug?
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    • Prodrug
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     Do these functional groups need to hydrolyze to free –OH’s before the drug can be active at the corticoid receptors?
    No, only the C21 ether needs to be hydrolyzed
Author:
kyleannkelsey
ID:
268466
Card Set:
Chem Basis: Steroids 3
Updated:
2014-03-30 22:19:32
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Chem Basis Steroids
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Chem Basis: Steroids 3
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Chem Basis: Steroids 3
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